Yeast tRNATrp genes with anticodons corresponding to UAA and UGA nonsense codons.
AUTOR(ES)
Kim, D
RESUMO
Naturally occurring suppressor mutants derived from tRNATrp genes have never been identified in S. cerevisiae. Oligonucleotide-directed mutagenesis was used to generate potential ochre and opal suppressors from a cloned tRNATrp gene. In vitro transcription analyses show the ochre suppressor form of the gene, TRPO, accumulates precursors and tRNA in amounts comparable to the parent. The opal suppressor, TRPOP, accumulates 4-5 fold less tRNA. Both forms of the gene are processed and spliced in vitro to produce tRNAs with the expected base sequences. The altered genes were subcloned into yeast vectors and introduced into yeast strains carrying a variety of amber, ochre, and opal mutations. When introduced on a CEN vector, neither ochre nor opal suppressor forms show suppressor activity. Deletion of the CEN region from the clones increases the copy number to 10-20/cell. The opal suppressor form shows moderate suppressor activity when the gene is introduced on this vector, however, the ochre suppressor form exhibits no detectable biological activity regardless of gene copy number. Northern blot analyses of the steady state levels of tRNATrp in cells containing the high copy-number clones reveal 20-100% increases in the abundance of tRNATrp.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=331181Documentos Relacionados
- Codon specificity of UGA suppressor tRNATrp from Escherichia coli.
- Suppression of UAA and UGA termination codons in mutant murine leukemia viruses.
- Spiroplasma citri UGG and UGA tryptophan codons: sequence of the two tryptophanyl-tRNAs and organization of the corresponding genes.
- Modification of the anticodon triplet of E.coli tRNAMetf by replacement with trimers complementary to non-sense codons UAG and UAA.
- Identity elements and aminoacylation of plant tRNATrp.